Carboxyl Group as a Radical Scavenging Moiety: Thermodynamics of 2H+/2e– Processes of Phloretic Acid

Phloretic acid is one of the most abundant colon catabolites of various classes of polyphenols (e.g., polymeric proanthocyanidins, tea catechins, and ellagitannins). In this paper thermodynamics of 2H+/2e– radical scavenging mechanisms of phloretic acid was studied. For the first time the involvement of carboxyl group in double hydrogen atom transfer (dHAT), double electron transfer-proton transfer (dET-PT) and sequential double proton loss double electron transfer (SdPLdET) processes was investigated. Obtained results indicate that phloretic acid possesses potential for inactivating radicals of different characteristics (HO•, HOO•, CH3O•, CH3OO•, CH2=CH–O–O•, PhO•, Cl3COO• etc.) via dHAT and SdPLdET mechanisms. Because phloretic acid is usually better absorbed than its precursor molecules, it may contribute to health benefits associated with regular intake of polyphenol-rich diet by direct scavenging of radicals.